Turkish Journal of Zoology Turk J Zool (2013) 37: 717-722 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1301-23

Reproductive biology of the greater lizardfish, tumbil (Bloch, 1795), in Bushehr coastal waters of Iran

1 2, 2 1 Akbar ABASZADEH , Yazdan KEIVANY *, Nasrollah Mahboobi SOOFIANI , Ali FALAHATIMARVAST 1 Department of Fisheries, Faculty of Natural Resources, Persian Gulf University, Bushehr, Iran 2 Department of Natural Resources (Fisheries Division), Isfahan University of Technology, Isfahan, Iran

Received: 17.01.2013 Accepted: 27.05.2013 Published Online: 04.10.2013 Printed: 04.11.2013

Abstract: A total of 691 specimens (114 males, 538 females, and 39 immature specimens) were collected from Bushehr coastal waters of the Persian Gulf from February 2007 to February 2008 to study the reproduction of this species along with its histological gonadal development. Mean absolute and relative fecundity was 263,162 ± 31,046 and 273 ± 27, respectively. The oogonia and oocyte diameter ranged between 6 µm and 875 µm with a mean of 318 µm. The relationship between fecundity and total weight was F = 192.85W + 69,291. Monthly changes in the gonadosomatic index exhibited a higher value in May and October in both sexes (P ≤ 0.05). Observations on the seasonal distribution of maturity stages and seasonal fluctuations in the gonadosomatic index confirmed recent findings that the spawning periods have 2 peaks, a higher peak in May and a lower peak in October. The hepatosomatic index and gonadosomatic index fluctuations were similar in females but different in males. Males and females ofSaurida tumbil reach first sexual maturity at 25.5 and 27 cm, respectively. The sex ratio was 1M:5F (P ≤ 0.001). The simultaneous presence of postovulatory follicles and yolk globules in some ovaries indicated that this species is a multiple spawner.

Key words: , fecundity, gonadosomatic index, ova diameter, Persian Gulf, Saurida tumbil,

1. Introduction have a long reproductive cycle, whereas some other fishes The greater lizardfish, Saurida tumbil, is a member of spawn all their eggs in a short period (Yoneda et al., 1998). the family Synodonthidae, which is widely distributed In previous studies, there has been uncertainty about the through the Indian Ocean, Pacific Ocean, Gulf of Oman, greater lizardfish being a multiple spawner and a suspicion and Arabian Sea, and it is one of the most commercially of it being hermaphroditic, but due to lack of histological important common coastal fish in the Persian Gulf (Fisher works and adequate samples, this could not be confirmed and Bianchi, 1984; Kuronuma and Abe, 1986; Randall, (Soofiani et al., 2006). The present study was therefore 1995; Carpenter et al., 1997). The greater lizardfish inhabits carried out to investigate the reproduction and histological sandy or muddy bottoms or coral reefs from the coastal gonadal development of the species in Bushehr Province, line to a depth of 100 m. The greater lizardfish is the most southern Iran. abundant species in both number and weight found in demersal fish assemblages in Bushehr Province on the 2. Materials and methods Persian Gulf. In the Bushehr coastal waters, the greater The study was carried out on a S. tumbil population in lizardfish is caught by several fishing methods, including the Persian Gulf. Monthly collections were made from bottom trawl and gill net; however, its abundance has February 2007 to February 2008, where a total of 652 decreased steadily in the world in recent years (www. adult S. tumbil specimens (114 males and 538 females) fishbase.com, accessed on 3 May 2013). were collected from commercial fishing boats in Bushehr Ecological factors affect the biological and reproductive Province, Iran. These specimens were caught by standard characteristics of fish populations, so investigations of these bottom trawls at a depth of about 50 m from usual fishing factors should be carried out periodically. Determining grounds during the early morning hours, and they were the reproductive cycle of a species within its native range brought to the laboratory fresh on ice. is necessary to understand its reproductive biology. It is Total length (TL) and body weight (BW) were recorded important to realize that fishes with fractional spawning for the specimens to the nearest 1 mm and to the nearest * Correspondence: [email protected] 717 ABASZADEH et al. / Turk J Zool

1 g, respectively. The gonads were dissected from the fish Duncan’s test, were used (Zar, 2000). All statistical analyses and weighted to the nearest 0.01 g (GW), while the sex was were carried out using SPSS 16 (IBM). determined by visual inspection. The gonadosomatic index (GSI) was calculated 3. Results using the following formula: GSI (%) = 100 × GW / BW Length frequency of the S. tumbil specimens collected in (Nikolsky, 1963; Biswas, 1993). In the spawning-capable this study is shown in Figure 1. The most abundant group fish with flowing oocytes, 3–5 subsamples of known of males belonged to the size group of 23.1–28 cm and of weight were extracted from different (anterior, middle, the females to the size group of 43.1–48 cm. Age of the fish and posterior) parts of the ovary lobes after the ovaries ranged between 1 and 8 years. The age at first maturity was were weighed. Each subsample was weighed to the nearest 2 years for both sexes at sizes (TL) of 25.5 cm for males 0.001 g, and then all oocytes in each subsample were and 27 cm for females. The sex ratio was close to 1M:5F; counted. Histology of ovarian tissue was used to describe however, in the smaller size classes it was 2M:1F (χ² = 16.6, maturation, spawning season, and reproductive periodicity df = 1, P ≤ 0.05). of greater lizardfish in the Persian Gulf. For both sexes, Mean total absolute and relative fecundity (±SD) the gonads were preserved in 10% formalin solution for was 263,000 ± 31,000 and 273 ± 27, respectively. The subsequent histological analysis. The hepatosomatic index minimum and maximum ova diameter was 6.71 µm (HSI) was calculated monthly to determine the feeding (stage 1) and 875.34 µm (stage 5), with a mean of 320 ± status of the fish throughout the year: HSI = (wet weight of 60 µm. The relationship between the fecundity and total liver / total wet weight of fish) × 100 (Biswas, 1993). weight of the fish was F = 192.85W + 69,291 (Figure 2). Ten percent of the individuals from monthly sampling The GSI was 0.6 in males and 0.8 in females at the first were randomly chosen for the histological studies. Gonads sampling in February 2007. It began to increase in both were dehydrated, embedded in paraffin, and sectioned with sexes and peaked in May (1.7 in males and 6.3 in females). a microtome (MICRON model: Belgium) to a thickness of It then dropped in June, began to increase in July, and 5–7 µm, following Hinton’s (1990) conventional processing. peaked again in October (ANOVA, df = 12, P ≤ 0.05). Staining was performed using Mayer’s hematoxylin and The same trend was observed for HSI in the females, but eosin. Description of the developmental stages of the it was almost constant in the males during this period ovaries was based on Brown-Peterson et al. (2011). (Figures 3–5). Oocyte development of greater lizardfish Scales were used for age determination. For this was consistent with batch spawning that exhibits group purpose, 5 to 10 scales were taken from the flank and synchronous development. Ovaries contained oocytes at examined under a binocular microscope. Scales were kept various stages of development as confirmed by histological in 3% NaOH solution for 24 h and then washed in distilled preparations. The oocytes of S. tumbil were classified into water and treated with 96% ethyl alcohol (Nikolsky, the following developmental stages: 1963). After cleaning, scales were examined under a 1. Developing: Nucleoli distributed around the inner stereomicroscope for age determination. Otoliths of some margin of the nuclear membrane (Figure 6A). The oocytes’ fish were used for age validation. No significant differences cytoplasm was stained deeply with hematoxylin. Some in age determination by otoliths and scales were observed. large round and basophilic nucleoli were observed in the For comparison of 2 means, the t-test, and for multiple nucleus. The follicle layer surrounding the oocytes became comparisons of means, one-way ANOVA followed by visible. A large number of yolk vesicles were present within

Immature Female Male 100%

80% y =192.85 x + 69291 R² = 0.4455 60% 500,000 450,000 40% 400,000 350,000 300,000 Length frequency 20% 250,000

Fecund t y 200,000 0% 150,000 100,000 50,000 >53.1

18.1-23 23.1-28 28.1-33 33.1-38 38.1-43 43.1-48 48.1-53 0 350 550 750 950 1150 1350 1550 Total length(cm) Total we ght (g) Figure 1. Length frequency for greater lizardfish (Saurida tumbil, Figure 2. Relationship between fecundity and total weight in Synodontidae) collected in this study. greater lizardfish (Saurida tumbil, Synodontidae).

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Stage III Stage II Stage I 100%

90% Stage III Stage II Stage I 100% 80% 90% 70% 80% 60% 70% f spec­mens

o 50% 60% 50% 40% 40% 30% Percentage 30% 20% Percentage of spec mens 20% 10% 10% 0% 0% Feb Mar Apr May Jun Jul Aug SepOct Nov Dec Jan Feb FebMar AprMay Jun Jul AugSep OctNov DecJan Feb Months Months Figure 3. Monthly variations in the sexual stages of male greater Figure 4. Monthly variations in the sexual stages of female lizardfish (Saurida tumbil, Synodontidae). greater lizardfish (Saurida tumbil, Synodontidae).

0.07 yolk globules completely fused together (Figure 6E). Large eggs were distinguishable. 0.06 Male GSI 3. Regression: The ovaries entered this stage after 0.05 Female GSI spawning of egg batches. In this stage, various types Male HSI of postovulatory follicles with different morphological 0.04 Female HSI features were observed (Figure 6F). The ovaries were 0.03 inflamed and their cavities were free of ova. Postovulatory follicles were characterized by a large follicular lumen 0.02 formerly occupied by the oocytes. 0.01 4. Regenerating: The yolk globules were liquefied, with the nucleus, empty follicles, and unspawned ripe eggs 0 interspersed among them (Figure 6G). Male Saurida tumbil has the lobular type of testes. Figure 5. Monthly variations in the GSI and HSI of greater Lobules are delimited by connective tissue fibers within lizardfish (Saurida tumbil, Synodontidae) (confidence intervals, the lobular wall. The germ cells have been classified 95%). as: immature stage, with only primary spermatogonia; developing stage, with primary and secondary spermatocytes and spermatids; spawning stage, with the cytoplasm (Figure 6B). Size of the oocytes became spermatozoa; regressing stage; and regenerating stage. larger and less basophilic, but they were still stained with Early spermatogonia occurred singly, almost completely hematoxylin–eosin. The larger follicles became thicker. surrounded by Sertoli cells, and were dispersed throughout Yolk globules appeared first in the peripheral cytoplasm the immature testes. From stage I to V the size of germ cells of the oocytes as minute granules (Figure 6C). They became smaller, and in stage IV the testis was full of semen increased in size and number and occupied most of the and a group of spermatozoa was oriented as an umbrella. cytoplasm. The follicle layer became thicker and the At stage V, the testis was wrinkled (Figure 7). nucleus was located in the central area of the oocytes. The entire cytoplasm was then filled with many yolk globules. 4. Discussion The nucleus migrated from the center to the pole Information regarding the reproductive biology of S. where the micropyle is located (Figure 6D). At the end tumbil species in the Persian Gulf is quite limited and the of this stage, the nuclear envelope broke down (germinal sample sizes of previous studies were inadequate (e.g., vesicle breakdown) and the yolk globules almost fused in Soofiani et al., 2006). The sex ratio in this species is not the peripheral cytoplasm. balanced (annual average rate M/F = 0.2). The high ratio of 2. Spawning-capable: The ovaries occupied almost the females to males found in this study supported the results entire body cavity. Oocytes became irregular in shape and of Soofiani et al. (2006) as 1M:5F and Taghavi Motlagh

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Figure 6. Ovary development in female greater lizardfish (Saurida tumbil, Synodontidae). A) Perinucleolus stage. B) Yolk vesicle stage. C) Yolk globule stage. D) Migratory nucleus stage. E) Mature stage. F) Postovulatory follicles stage. G) Atretic stage. At: Atresia, CA: Cortical alveoli, C: Cytoplasm, F: Follicle layer, Mn: Migratory nucleus, N: Nucleus, Ne: Nucleolus, POF: Postovulatory follicles, Yg: Yolk globule, YV: Yolk vesicle, Z: Zona radiata.

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Figure 7. Testicular development in male greater lizardfish. A) Different stages of sperm development from developing to spawning stages. B) Spermatids. C) Spawning stage with spermatozoa (III). D) Regression stage (IV). SC1: Primary spermatocytes, SC2: Secondary spermatocytes, SD: Spermatids, SG: Spermatogonia, ST: Sertoli cells, SZ: Spermatozoa. et al. (2012) as 1M:4.6F. The highly skewed sex ratio of Fecundity varied from a mean of 140,742 ± 8541 eggs greater lizardfish may have several underlying causes. It is per female at a weight of 399 g to a mean of 456,985 ± possible that male S. tumbil may not commonly inhabit 24,218 eggs per female at a weight of 1470 g. This was the depth zone where the majority of fishing efforts for this positively correlated with fish weight, body length, age, species are concentrated. Furthermore, sexual differences and gonad weight. The fecundity of this fish in a nearby in growth, mortality, and the immigration of females population ranged between 74,000 and 250,000 eggs for reproduction were suggested as reasons for these (Soofiani et al., 2006). observations. Sex ratio is also age-dependent; in older fish, Compared to the range of GSI values found in our study, the females dominate in number (Bakhsh, 1996). These Soofiani et al. (2006) reported these values as 4.2 (March) results might also be indicative of a somewhat biased and 0.26 (December), respectively, in their study. It may sampling not fully representative of the stocks. differ from place to place due to the pattern of energy use, The scanty reports available on minimum size at water temperature, different salinity, population, disease, sexual maturity in S. tumbil are unequivocal in that males and nutrition, as seen in this species. mature at smaller sizes than females, although the exact Morphologically, the follicular atresia was revealed by sizes at maturity may differ from one place to another hypertrophy of the granulose layer, followed by digestion (Budnichenko and Dimitrova, 1979). Similar observations of the vitellin envelope, split of the cytoplasmic cortex, are made in the present study, as also reported from the and nuclear membrane decomposition (early atresia). Arabian Sea (Budnichenko and Nor, 1978), from the Red This was followed by rapid phagocytosis of the oocyte yolk Sea as 19 cm (Bakhsh, 1996), from the Indian Ocean as 23 (intermediate atresia) and formation of the atretic body cm (Rajkumar et al., 2003), and from the Persian Gulf as by the transformed follicular and blood-borne cells with a 29.9 cm (Taghavi Motlagh et al., 2012). capillary infiltration (late atresia).

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The histological sections of prespawning ovaries discrepancies can perhaps be explained by the ecological showed no empty follicles, indicating that the spawning differences that exist among the habitats and different season had not yet begun. During the year, different populations. combinations of oocyte types were seen within the ovary; During the spawning season, the postovulatory oogonia and previtellogenic oocytes were observed during follicles were observed together with oocytes at yolk stage the entire year. Fully grown and mature oocytes were in histological sections of the ovaries of greater lizardfish, detected in May and October, when the highest female GSI as seen in another close lizardfish species (Budnichenko values were observed. These results are in line with other and Dimitrova, 1979). Gonad histology demonstrated that studies (Budnichenko and Nor, 1978; Soofiani et al., 2006). greater lizardfish S. tumbil exhibits the group-synchronous In this study, based on the GSI values and histological type of oocyte development. observations and direct observation of gonads, it was revealed that the S. tumbil population spawns in May Acknowledgments and October in the Persian Gulf. Rao (1983) reported a We would like to thank all the fishermen who provided the spawning period for S. tumbil ranging from September to fish samples and those who helped us with the laboratory March with a peak in November–December in the Bay of work. This study was financially supported by Isfahan Bengal. Soofiani et al. (2006) reported 2 spawning periods, University of Technology and Persian Gulf University of one in October and another in March. The existing Bushehr.

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